Auxiliary plant for use with boilers of heading 8402 or 8403 — HTS 8404
Auxiliary plant for use with boilers of heading 8402 or 8403 (for example, economizers, super-heaters, soot removers, gas recoverers); condensers for steam or other vapor power units; parts thereof
Chapter 84 › Heading 8404
2026 HTS Rev 19 Synced Rules verified Operational
Written to help non-specialists understand this page. Rates, dates, and legal facts come from the official records above and on the linked source.
HTS heading 8404 groups equipment that supports boilers or steam-generation systems, rather than the boiler itself. It covers auxiliary plant used with boilers of heading 8402 or 8403—such as economizers, super-heaters, soot removers, and gas recoverers—as well as condensers for steam or other vapor power units. The heading also includes identifiable parts of these goods.
To reach the correct 8-digit HTSUS code, first identify the product’s function and confirm that it is designed for use with the specified boiler or vapor power equipment. Then use the subheadings and statistical provisions to narrow the classification, commonly by the equipment type and, for parts or other provisions, by the relevant material or construction. The exact code depends on the tariff text and the product’s objective characteristics, so unusual or multifunctional equipment may require customs-broker or classification-specialist review.
What to check
- Identify the equipment’s primary function: economizer, super-heater, soot remover, gas recoverer, condenser, or a part.
- Confirm that the item is for a boiler of heading 8402 or 8403, or for a steam or other vapor power unit, rather than for general industrial use.
- Determine whether you are classifying a complete unit, a separately presented part, or a component that has another more specific HTS provision.
- Check the product’s construction, materials, technical specifications, and intended installation against the wording of the relevant 8-digit provisions and statistical suffixes.
- Keep catalogs, drawings, model numbers, and manufacturer statements showing the item’s function and compatible equipment; obtain broker advice when the classification is uncertain.
HTS heading 8404 summary
Auxiliary plant for use with boilers of heading 8402 or 8403 is a 4-digit product category containing 3 published product-code lines in this snapshot. A heading does not carry one universal duty rate; classification must be narrowed to the line matching the product facts.
How to find your code in this category
A heading is a product category. To get the exact duty, narrow from this 4-digit heading to a sub-category (usually by material), then open the 8-digit code that matches your product.
Open any code in the tables below to see its exact duty rate, a duty calculator (enter your shipment value → estimated duty and landed cost), the rate-change history chart, and the country-by-country breakdown (including Section 301/232 add-on duties).
Why you have to click in: a single category can contain products with very different duties. The rate depends on the specific product — its material and construction — and on the country of origin, and those only get pinned down at the 8-digit code level. That is why this page points you to codes instead of showing one rate for the whole category.
Product codes & duty rates
👇 Each row is a specific product code — click a blue code to open its full page with exact duty rates by country, the rate-history chart, and a duty calculator. 👉
| Code | Description | General (MFN) | Special | Column 2 |
|---|---|---|---|---|
| 8404.10.00 👉 | Auxiliary plant for use with boilers of heading 8402 or 8403 | 3.5% | Free | 45% |
| 8404.20.00.00 👉 | Condensers for steam or other vapor power units | 5% | Free | 45% |
| 8404.90.00.00 👉 | Parts | 3.5% | Free | 45% |
"Special" shows the free-trade-agreement rate; open a code to see exactly which countries qualify.
Common questions
What products fall under HTS heading 8404?
Auxiliary plant for use with boilers of heading 8402 or 8403 (for example, economizers, super-heaters, soot removers, gas recoverers); condensers for steam or other vapor power units; parts thereof. To classify a specific item you must pick the matching sub-category and 8-digit code above; the right choice usually depends on the material and construction of the product.
How do I choose the right code within this category?
Start from the sub-categories (typically divided by material—for example cotton versus man-made fibers), then open the active 8- or 10-digit code that matches the product. When unsure, a licensed customs broker or a CBP binding ruling can confirm the classification.
Reference information only, not customs, legal, or classification advice. Confirm the current code and rate against the official HTS before you import.